1. Field of the Invention
The present invention relates to the detection of blood pooling near the surface of the body, and more specifically, it relates to technology for the diagnosis of sub-dural or epi-dural hematoma.
2. Description of Related Art
At present, there is no non-invasive way to check patients for hematoma other than a paramedic's verbal/tactile evaluation and x-ray computed tomography (CT). A hematoma can exist in a patient with few or no symptoms, and can grow rapidly, killing or rendering the patient comatose within as little as 10 minutes.
In one of the current procedures for screening head injury patients, paramedics or first responders to the scene of an accident evaluate the patient state (through questions and observations of the patient's behavior) and the accident situation (degree of damage to cars, height of fall, etc.). In cases of severe head injury or concussion, there exists a ranking system called the Glasgow coma scale. The patient is ranked based on observation of reflex response, eye movement, breathing, ability to speak, etc. The ranking can be quite inaccurate if the patient is drunk or has other injuries that impact the ranking procedure (i.e. severe loss of blood, patient is in shock, blocked airway, etc.).
In another currently used head injury screening procedure, patients with known head trauma or suspected head trauma are then sent for a CT scan. The decision to order a CT scan is done conservatively, i.e., even if it is not clearly warranted. This is a precautionary measure since a patient with a sub-dural or epi-dural hematoma may not present with clear symptoms at the outset. Sub-dural or epi-dural hematoma can cause the patient to lapse into a coma or go into respiratory arrest. Time is the critical parameter in determining mortality or morbidity that will result from the injury.
The cost of a CT scan is high. A typical head scan is about $500-$800, and can cost much more if the patient must be sedated or closely monitored during the scan. In many cases, many scans of a single patient are necessary to monitor the development of his/her condition.
The total time required for a scan is about 15 minutes using a helical scan device (faster than the standard CT scanners). If the scanner is physically located right in the emergency room, this time can go down to 5 -10 minutes. However, the actual time to diagnose a hematoma (or other problem) is usually limited by patient transportation, preparation and the need to have a radiologist read the scan. If the scan must be sent out of the emergency room for reading, the overall time can be between 30 minutes and 3 hours. A hospital may need to do many CT scans a day. At a typical ER, between 70% and 90% of CT head scans are unnecessary--i.e., are done for precautionary reasons and yield a negative result.